Transformer



oct. 23, 192s. l 1,688,748'

W. E. PAUL TRANSFORMER Filed Feb. 9, 1928 Inventor:

Wiliam Epaul, by MM His Attorney.

Patented oct. 23,f192.

f UNITED STATES PATENT OFFICE.

-WIII'JLAH'l E. PAUL, OF SC-'H-ENECTADY, NEW YORK, ASSGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK.

TRANSFORMEE..

Application filed February 9, 1928. Serial No. 253,173.

My invention relates to transormers and more particularly to high voltage transformers of small capacity and adapted to be used where high accuracy is not essential. Transformers of this character may be used satisfactorily to operate relays for instance. good inductive coupling between the two windings of a transformer requires that they be close together so that the leakage iux may not be excessive. It is diiiic-ult to place the windings close to ether, however, if the voltage between them is very high because there must be suiicientinsulation between them to gvithstand the high voltage. The general object of the invention is to provide an improved transformer construction iny which the windings may be reasonably close together even though the difference between their voltages maybe very high.

The invention will be better understood from the following Cdescription taken in connection with the accompanying drawing in which Fig. 1 is a sectional View of a transformer constructedv in accordance with the invention and Fig. 2 is a similar view of a modified form ofothe invention.

Like reference characters refer. to similar parts in 'both figures of the drawing.

In the form of transformer shown in Fig. 1, the primary winding 10 surrounds a magnetic core` 11 and is connected by conductors 12 and 13 to 7the two primary terminals 14 and 15. The winding 10 and its core 11 are enclosed in a closed casing 16 of insulating material such as glass which is highly 'evacuated. This casing is of elongated form with the windi 1() and core 11 midway between its two en s. A secondary winding 17 on a spool 18 surrounds the central portion of the casing 16so that this secondary winding also surrounds'the primary winding 1() and core 11. This construction brings the two v windings reasonably close together so that the magnetic coupling between them will be satisfactory. The secondary winding 17 isv surrounded by ar layer of magnetic material 19 which may comprise a plurality of magnetic rods or wires laid parallel to the axis of the two windings 10 and 17 to provide a return path for the magnetic iiux in the core 11. This magnetic layer 19 may be held in place by an outer insulating covering 20. The two end portions of the casing 16 are. long enough to prevent arc over between the terminals 41%41 and 15 and the secondary winding 17. The end "portions of the casing 16 may also be corrugated as shown to increase the surface leakage paths between the secondary winding and the terminals.

Ordinary dry air at atmospheric pressure is of. course a very 'good insulator. As the pressure is decreased, the dielectric strength of the air decreases' at iirst but finally it betion. The primary winding 10 yand core 11 .are suspended in the casing by the conductors 12 and 13 and out of contact with the sides of the casing so that they are completely separated and insulated from the casing walls by a region of high vacuum. The electrical and magnetic losses in the primary winding and core appear as heat which cannot of course be dissipated to any substantial extent through the vacuum but this heat may low through the conductors 12 and 13 to theter'- minals 14 and 15 which may be provided with heat conductive discs 21 to increase the rate of dissipation of this heat.

In the form of the invention shown in Fig. 2, the primary winding 10 surrounds the core 11 and both winding and core are surrounded by an elongated casing or tube 16 of insulating material such as glass. ,The tube 16 comprises twoconcentric spaced walls with the space between them highly evacuated, the ends ofthe two walls being sealed together to maintain the vacuum. The secondmagnetic iiux in the core 11. The vacuum` between the walls of the tube 16 is interposed between'the secondary winding and the primary winding and core. The primary winding and its core in the arrangement shown in f some cooling medium such as air through the A Fig.V 2 may be easily'cooled by a current of tube 16. f

In both forms of the invention which have been described, a -region of high vacuum is interposed between the primary winding which may be at very high voltage and the secondary winding 17 which mayjbe at a very much lower voltage. The highly ei cient insulation provided by'l the' vacuum makes it practicable to arrangethe windings substantially closer together than is the case' ti with ordinary insul on such as has been heretofore used for this purpose, the result being generally better operating characteristics suc-h as lower reactance and more un`i` lform voltage ratio as the load on the transformer is varied.

The invention has been explained by describing and illustrating certain embodiments thereof but it will be apparent that various changes may be made Kwithout departin from th'e Vscope of the invention as tlatine in the appended claims.

What I claim as new and desireto secure by lLetters Patent of the United States,.is

1. A transformer includingA a primary winding, ay closedc'asing having a high vacuum surrounding said winding, anda secondary winding surrounding said casing and primary winding.

2. A transformer including a magnetic core, a primary winding surrounding said core, a secondary winding surrounding said primary winding and cre and means providing an insulating region voffhigh vacuum between said secondary winding and said primary winding and core. y

3. A transformer including a magnetic core, a primary winding surrounding said core, a highly evacuated*casingsurrounding said primary winding and core, a secondary winding surrounding said casing, and magnetic means providing a return path for magnetic flux outside said secondary winding.

In witness/whereof, I have hereunto set my hand this Sthvday ofFebruary, 1928. i

, WILLIAM E. PAUL. 

